Abaixo está uma instrução que descreve uma tarefa de geração de SQL, combinada com uma entrada que fornece mais contexto sobre os esquemas de tabela disponíveis. Escreva o código SQL que responda adequadamente à solicitação
 ###Instrução: Na grade 15, quantas voltas houve antes de terminar com um tempo de exaustão?
 ###Tabelas: CREATE TABLE wins_60 (wins_60_id AUTO_INCREMENT PRIMARY KEY, Outcome VARCHAR, Date INT, Tournament VARCHAR, Surface VARCHAR, Partner VARCHAR, Opponents in the final VARCHAR, Score in the final VARCHAR) CREATE TABLE free_play (free_play_id AUTO_INCREMENT PRIMARY KEY, Developer(s) VARCHAR, Release date VARCHAR, Required OS VARCHAR, Genre VARCHAR, Type VARCHAR) CREATE TABLE season_5_1992 (season_5_1992_id AUTO_INCREMENT PRIMARY KEY, Number in series INT, Number in season INT, Title VARCHAR, Directed by VARCHAR, Original air date VARCHAR, Production code VARCHAR) CREATE TABLE classification (classification_id AUTO_INCREMENT PRIMARY KEY, Driver VARCHAR, Constructor VARCHAR, Laps INT, Time/Retired VARCHAR, Grid INT) CREATE TABLE episodes_and_ratings (episodes_and_ratings_id AUTO_INCREMENT PRIMARY KEY, Episode INT, First broadcast Denmark ( DR1 ) VARCHAR, Official TNS Gallup ratings INT, First broadcast UK ( BBC Four ) VARCHAR, Official BARB ratings INT)  
SELECT SUM Laps FROM classification WHERE Time/Retired = exhaust AND Grid < 15